We will study the photochemistry of polycyclic aromatic amino azides which bind to DNA by intercalation. We will use low temperature Matrix IR, UV-Vis, fluorescence and EPR spectroscopy to identify the specific intermediate(s) produced by photolysis of ethidium azide and proflavine azide. We will photolyze these azides intercalated into mini duplexes of self complementary dinucleotides. The products of these photoreactions will be identified by X-ray crystallography. We will also prepare polyfluorinated derivatives of ethidium azide and proflavine azide. This should greatly simplify the azide photochemistry and increase the absolute reactivity of the photogenerated intermediates. The latter point will increase the chances of covalent attachment in the binding site. We will study these polyfluorinated azides in solution and bound to mini duplexes by laser flash photolysis to obtain the absolute lifetime of the labeling intermediate.